Modern automotive vehicles employ increasing numbers of electrically powered equipment systems. Examples of these systems include the engine control system,(e.g., automatic transmission, brakes, traction control, steering, suspension, air conditioning), the signaling and accessory system (e.g., lights, horn, instrument panes indicators, service monitor systems, radio), and various motors (e.g., power seats, power windows, door locks, trunk lids, windshield wipers and washers). Supplying these systems with the necessary levels and amounts of electrical power has become increasingly complex and difficult. The power distribution system typically includes a housing that houses several components, such as, microprocessors, solid state drivers, printed circuit boards, wiring, diodes, resistors, capacitors, fuses, relays, and the like.
FIG. 1 is a schematic diagram of a segment of a power distribution system used in an automotive vehicle that illustrates such complexity. As shown, engine compartment 10 includes a power distribution unit 12, (such as a fuse box, relay box, power distribution center, junction block), mounted in engine compartment 10. Unit 12 includes a plurality of relay or driver units 14A-14I which produce outputs to load/devices 16A-16I, located outside of unit 12, by means of electrical conductors 18A-18I. Engine compartment ECU 20 produces output/relay control signals transmitted over electrical conductors 22A-22E to respectively control relay or driver units 14A-14E. Interior ECU 24 located in the interior 26 of the vehicle produces output/relay control signals transmitted over electrical conductors 28A-28D to respectively control relay or driver units 14F-14I. Unit 12 also receives signals form switch or sensor units 30A-30D over electrical conductors 32A-32D and transmits the signal from unit 30A to ECU 20 over electrical conductor 22F and the signals from units 30B-30D to ECU 24 over electrical conductors 28E-28G. ECU 24 also produces an output signal transmitted over electrical conductor 28H to unit 12 and from unit 12 over electrical conductor 32E to low current load/device 34. Unit 12 may include a printed circuit board, be hard wired, or utilize other technology or a combination. In FIG. 2, electronics unit 36 includes a printed circuit board with appropriate electronic components and sealing for carrying out the functions of unit 36. Unit 36 communicates with ECUs 20 and 24 and other ECUS over bus system 29′.
In FIG. 1, a communication bus 29 (such as a CAN bus), connects ECU 20 and ECU 24 together and with other ECUs. Electrical conductors 22A-22F and 28A-28G can be hardwired to unit 12 devices or can be terminated by an electrical connector plugged into unit 12. The complexity of the wiring in FIG. 1 and having a printed circuit board as in FIG. 2 in unit 12 are disadvantageous. The extensive wiring in FIG. 1 is labor intensive. The printed circuit board in unit 12 can be degraded by the heat generated by the electrical power components mounted in unit 12. Moreover, the printed circuit board in unit 12 raises the need for sealing or partially sealing the power distribution unit.
There is thus a need for a solution to these problems.